I just bought Crysis Warhead and loaded up the mutliplayer and jumped into a match. Everything is really cool except I have practically no idea what is going on... Is there a guide out there that explains Crysis Wars? I tried google but had no luck.
Also, I start off with a pistol but everyone else has machines and shotguns so I easily get destroyed. Where do you pick up weapons? Does it have to do with your rank?

No...maybe you were in a weird server, but they spawn around the map, and usually  where you spawn there are some around you to begin with...if not you gotta make do while you go around and just check out places, but you'll eventually get the weapon spawns. it depends what gametyp you're playing, so I can't tell what you exactly are doing, the pure team based things weapons aren't always right in your base you spawn at, but they are always nearby, or a drive to the next base away.